Silencer for rock drills



June 3, 1941.

Filed May 16, 1940 N? -EN INVENTOR ryeHerer.

HIS ATTORNEY ww/w www@ f a mu/ Q ///7///////f EY# :L wwmuwmnw I... D f, f /V/ /w/// -K h f lf Tf1 WEI Patented June 3, 1941 SILENCER FOR ROCK DRILLS George H. Fuehrer, Phillipsburg, N. J., assignor to Ingersoll-Rand Company, New York, N. Y., a corporation of New Jersey Application May 16, 1940, Serial N0. 335,516

2 Claims.

'I'his invention relates to a silencer and, more particularly, it relates to a device for silencing the exhaust fluid of a pneumatic tool such as a rock drill.

The exhaust of pressure fluid from a percussion tool does not ow in a steady stream but occurs in impulses. When these impulses expand into the atmosphere, sound waves are set up which result in considerable noise.

One object of the invention is, therefore, to silence the exhaust of a percussion tool by transforming the impulse of the uid exhaust from the tool into a substantially constant stream and thus suppressing the customary attendant noise.

Another object is to provide a silencer which is simple, efficient, easy to install and repair, and inexpensive.

A further object is to prevent the exposure of the distributing valve mechanism of a pneumatic tool to the low temperature resulting from the expansion of the exhaust uid issuing from the cylinder of such pneumatic tool.

These and further objects will be apparent as the invention is described in connection with the drawing, wherein Figure 1 is an elevational, sectional view of a silencer constructed in accordance with the principles of the present invention, as applied to a rock drill, the latter being shown only in part.

Figure 2 is a sectional View along line 2-2 of Fig. 1.

Figure 3 is a sectional view along line 3-3 of Fig. 2.

Figure 4 is a sectional view along line 4-4 of Fig. 2.

With reference to Fig. 1, the silencer, generally indicated at I, is shown applied to a rock drill tool 3. The tool 3 comprises a cylinder, or casing, 5 having a front head 'I and a back head 9. The cylinder 5 is bored to provide a piston chamber II for the piston I3 which reciprocates therein and actuates the working implement I5 extending through the front head 1. The piston I3 also controls the free exhaust port Il for the piston chamber I I.

The piston I3 has a shank I9 extending into and slidably engaging the bushing 2I in the front end of the piston chamber II, which contacts the working implement I5. Pressure fluid to actuate the piston is supplied through ports and passages (not shown) to the distributing valve 23, of which only the outer casing is shown. This valve is disposed at the rear end of the cylinder and serves to distribute the fluid through other ports and passages (not shown) to the ends of the piston chamber II.

The silencer I comprises a tubular sleeve 25 surrounding the cylinder 5 and the distributing valve 23. The upper end of the sleeve 25 bears against a shoulder 21 formed on the annular extension 29 of a plate 3I seating against the back head 9. The tubular sleeve 25 is centralized with respect to the back head 9 by the projection 33 formed on the distributing valve 23 which extends through the plate 3| into the back head 9. Extending between the sleeve 25 and the cylinder 5, above the exhaust port Il, is an upper horizontal partition 35 secured to the tubular sleeve by welding, or in any other suitable manner. The partition 35 is preferably located immediately adjacent the exhaust port I'I and has a slide t on the casing 5 to prevent the flow of exhaust fluid in the direction of the valve 23 and thereby protect the valve against exposure to the low temperature of the fluid iowing from the exhaust port I'I into the sleeve 25. Another, or lower, partition 3l rests on the front head 'I and is formed by bending the end of the tubular sleeve 25 so that it extends inwardly to the cylinder 5. This partition, of course, may be formed separately from tubular sleeve 25 in a manner` similar to partition 35.

The two partitions 35 and 31 cooperate with the tubular sleeve 25 and casing 5 to form an exhaust chamber 39 designed to receive the exhaust fluid escaping from the piston chamber II through the free exhaust port II. Escape of pressure uid from the exhaust chamber 39 is permitted through one or more of the outlet ports 40 provided in the sleeve 25. Within the exhaust chamber 39 are a series of baiiie plates. As will be seen from Fig. 2, these baille plates are secured to the tubular sleeve by any appropriate means, such as welding.

On either side of the exhaust port I1 is a primary baiiie 43 extending from the partition 35 to a point near the lower partition 3l, or bottom of the chamber 39 as is apparent from Fig. 3. Spaced from the primary baiiles are secondary, or outlet port, bailles 45 secured to the tubular sleeve which extend from the bottom of the chamber toward the upper partition 35 but terminating below the partition 35, as will be seen from Fig. 4.

With this arrangement, the pressure fluid exhausting from the piston chamber II passes through the free exhaust port I'I and enters the primary chamber 49 defined by the baffles 43. From this space there is no path of escape for the fluid except through the passage provided between the bottom of the primary baffles 43 and the partition 3"! at the bottom of chamber 39 to the secondary chambers 55| defined by baffles 43 and 35 within the exhaust chamber 39. Escape from the secondary chambers will be through the space between the partition 35 and the top of the secondary baffles d5. Thereafter the pressure uid is free to exhaust to the atmosphere through the ports dii.

Any number of baffle plates and chambers formed thereby within the exhaust chamber 39 may, of course, be employed. The object of the bailes is to reduce the speed of the pressure'fluid flowing therethrough and, in that Way, provide a substantially constant flow of exhaust pressure fluid to the outer atmosphere to prevent the sudden expansion of a large quantity of pressure iiuid at regular intermittent periods.

Thus, by requiring the exhaust fluid to travel a path or" maximum length, a maximum dampening effect is secured and, consequently, there is very little noise attending the discharge of the exhaust fluid through the exhaust ports 40.

A further highly desirable advantage of the present invention is that the expanded uid in a sleeve clamped in assembled position by the back and front heads of a pneumatic tool can not reach the vicinity of the distributing valve mechanism and the temperature of the valve mechanism will, therefore, remain sufficiently high at all times to preclude the freezing of moisture entraine-:l in the pressure fluid passing through the valve mechanism and the consequent erratic action of the valve.

I claim:

l. In a silencer for a pressure iiuid actuated percussion tool, the combination of a casing having a piston chamber and an exhaust port for the piston chamber, valve means in the casing for effecting the distribution of pressure fluid to the piston chamber, a sleeve encircling and spaced from the casing and the valve means and cooperating vvith the casing to define an expansion chamber for the exhaust fluid issuing from the exhaust port, said sleeve having an outlet port for conveying fluid from the expansion chamber to the atmosphere, and means in the sleeve to prevent the flow of exhaust fluid through the sleeve in the direction of the valve means.

2. In a silencer for a pressure iiuid actuated percussion tool, the combination of a casing having a piston chamber an exhaust port for the piston chamber, valve means in the casing for eifecting the distribution of pressure fluid to the piston chamber, a sleeve encircling and spaced from the casing and the valve means and cooperating with the casing to deiine an expansion chamber for the exhaust iiuid issuing from the exhaust port, said sleeve having an outlet port for conveying fluid from the expansion chamber to the atmosphere, a plate in the sleeve immediately adjacent the exhaust port cooperating with the surface of the casing to prevent the iiow of exhaust iiuid through the sleeve in the direction of the valve means, and baiies in the expansion chamber 'to form tortuous path for the exhaust fluid between the exhaust port and the outlet port.

GEORGE E. FUEHRER. 

